Study on age-dependent pre-existing 2009 pandemic influenza virus T and B cell responses from Chinese population

Abstract

BackgroundThe outbreak of the 2009 H1N1 influenza pandemic (H1N1pdm) affected thousands of people in Mexico and the United States, and spread rapidly throughout the world from April 2009 to July 2010. To explore the age-specific prevalence of seroprotection against H1N1pdm infection, we estimated pre-existing humoral and cellular immunities of residents in Northern China against H1N1pdm and seasonal H1N1 virus in an age-dependent manner.MethodsAnonymous serum samples were collected from 1425 to 1434 adult healthy individuals before and after the pandemic outbreak, and then grouped by birth year 1913–1990. The antibody titers of H1N1pdm and seasonal H1N1 were determined using microneutralization (MN) assays, and the proportion of seropositive was estimated based on the year of birth. Separately, another 63 blood samples were collected in 2006 and prepared for analysis of virus specific memory B and IFN-γ+ T cells using the ELISpot assays.ResultsThe prevalence of pre-existing H1N1pdm-specific sero-antibodies in the elderly population (>60 years old) was 7.8%. The younger group, aged 19 to 60 years, exhibited a significant increase in seropositivity for H1N1pdm after the pandemic (4.9% before pandemic and 18.9% after pandemic, p < 0.05). The prevalence of H1N1pdm specific MBCs before the pandemic in the elderly (>60 years) and younger populations (<60 years) was 38% (8/21) and 48% (20/42), respectively (p = 0.6). The IFN-γ+ T cell responses to the pandemic and seasonal viruses were significantly lower in the elder group than those in the younger group (<60 years) (p < 0.05).ConclusionsPre-existing serum antibodies and memory B cells against H1N1pdm were low in all age group, whereas diminished memory T cell responses to this virus were observed in the elderly population both before and after the pandemic.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-017-2215-1) contains supplementary material, which is available to authorized users.

Epidemiological and clinical profile of Influenza A(H1N1) pdm09 in Odisha, eastern India

“…This finding also corroborates with the study of Jin Lv et. al, 2017 [7] reporting higher prevalence in elder age group which was not exposed previously. In our study it was observed that infection rate was higher among male individuals (50.6%) than females (49.3%) though the difference is not significant.…”

Influenza A haemagglutinin specific IgG responses in children and adults after seasonal trivalent live attenuated influenza vaccination

“…Previous Interestingly, a systems analysis suggested that the immune system of an individual is defined by specific exposure frequency, that an individual encounters in their lifetime [165]. From the experience during the last pandemic in 2009, older people who were born in 1940's had less severe infection due to the presence of pre-existing crossreactive anti pdm2009 antibody [166,167]. Several studies show that the stalk specific broadly neutralizing antibodies increase with age due to previous experience with divergent influenza viruses [168,169].…”

Study of Profile of Swine Flu Cases Admitted in Tertiary Care Hospital: Lessons Learned!

“…This finding corroborates with the study by Dwibedi et al 1 from Odisha from 2009 to 2017, where 29.7% of the cases were in the age group of 51 to 60 years followed by 22.7% in the age group of 31 to 40 years. Also, a study of Lv J et al 16 in 2017 reported higher prevalence in older age group, perhaps as this group was not exposed previously. However, studies from Queensland, 17 Saudi Arabia, 18 and the United States 19 showed cases to be more common in young age from 10 to 17 years.…”

“…the age group of 51 to 60 years followed by 22.7% in the age group of 31 to 40 years. Also, a study of Lv J et al16 in 2017 reported higher prevalence in older age group, perhaps as this group was not exposed previously. However, studies from Queensland,17 …”